Table of Mechanics

Mechanics (1C): Motion in One Dimension

Mechanics (1E): Relative Motion

Lecture Demonstrations

Motion in Two Dimensions

PIRA classification 1D

91 Demonstrations listed of which 50 are grayed out

Grayed out demonstrations are not available or within our archive and are under consideration to be added.

1D10. Displacement in Two Dimensions


Demonstration Name



Cycloid Generator

A large spool with a light bulb fastened to the circumference is rolled along the table. With and without the lights on. See University of Minnesota demo website.



A mechanical device that transforms rotational motion into rectilinear motion.


Vertical Mounted Bike Wheel

A bicycle wheel marked with a radial line turns about its axis.


Projected Circular Motion

A Turn table with a ball that rotates with an arrow on top is projected on a screen by a arc lamp with a pendulum above. See TPT 2(2), 79.


Measuring Angular Velocity of a Fan

Use an electronic strobe to measure the angular velocity of a fan blade or other rotating objects.

1D15. Velocity, Position, and Acceleration


Demonstration Name



Ultrasonic Detector and Students

Have a student walk toward and away from a sonic ranger while observing plots of position, velocity, and acceleration.


Kick a Moving Ball

Kick a moving soccer ball on the floor or hit a moving croquet ball on the lecture bench with a mallet.


High Road Low Road

Two objects start at the same velocity, one moves straight to the finish, the other traverses a valley. The problem: which one wins?


Catching the Train

A ball accelerating down an incline catches and passes a ball moving at constant velocity on a horizontal track.


Passing the Train

A ball accelerates down an incline with a stripped rope moving at constant velocity in the background. The moment the ball has the same velocity as the rope is strikingly obvious. Repeat with the rope at a different constant velocity.


Galileo's Circle

Several rods are mounted as cords of a large circle with one end of each rod top center. Beads released simultaneously at the top all reach the ends the rods at the same time. See Sutton M-93.


Brachistochrone Track

Three tracks - straight line, parabola, and cycloid are mounted together. Triggers at each end control a timer. See Sutton M-88 and M-89.

1D40. Motion of the Center of Mass


Demonstration Name



Styrofoam with Light

An odd shaped piece of Styrofoam with a light placed at the center of gravity is tossed in the air.


Center of Mass Disc

Throw a disc with uniform distribution and then offset the center of mass.


Hammer Toss

Mark the center of gravity of a hammer with a white spot. Throw it in the air and attach it to a hand drill to show it rotating smoothly.


Throwing a Bola

Three balls tied together and tossed in the air. See TPT 30(3), 180.


Spinning Block

A large wood block has two holes with felt tipped pens, one on the center of mass. Place the block on a large sheet of paper and hit off center with a hammer.


Air Table Center of Mass

A weighted block glides across an air table.


Photographing Center of Motion

Photographing the center of velocity of a variety of rigid bodies, using a high speed CCD camera. See AJP 58(5), 495.


Throw the Dumbbell

A dumbbell with unequal masses is thrown without rotation when the force is applied at the center of mass.


Earth-Moon System

Two unequal masses are fastened to the ends of a rigid bar with two holes in the bar. One hole is at the rod's center. The other hole is at the center of mass of this two body system.


Hanging Pendulum Glider

A double pendulum hangs from an air track cart with a mounted spot marking the center of mass. Set the system in oscillation and the spot will remain still or translate smoothly.


Pendulum Glider

A large glider with a pendulum on top of it. See Sutton M-125.


Momentum Pendulum

A pendulum support is free to move on rollers as the pendulum swings back and forth. See TPT 2(1), 33.


Air Track Inchworm

The center of mass of two carts coupled with leaf springs is marked with a light or flag. Show oscillation about the center of mass or constant velocity of center of mass. See University of Minnesota demo website.

1D50. Central Forces


Demonstration Name



Ball on a String

A tennis ball tied to a sting is whirled around in a vertical circle by hand.


Arrow on a Disk

Mount an arrow tangentially on the edge of a rotating disk.


Centripetal Force Apparatus

A large ball and a small ball fastened to opposite ends of a string which is threaded through a handle or glass tube. See AJP 29(3), 212.


Conical Pendulum

A wire is suspended from a ceiling mount and a bowling ball attached at the bottom. It is then put into an elliptical orbit thus acting as a conical pendulum.


Plane on String

A model plane flies around on a string defining a conical pendulum.


Carnival ride Model

A toy person is held on a vertical card at the edge of a turntable when the turntable is spun fast enough.


Swinging Up a Weight

An arrangement whereby a swinging 500g weight picks up a 1000g weight.


Pail of Water

A partially filled pail of water is whirled around in a vertical circle without spilling any water, illustrating centripetal force in conjunction with Newton's first and second laws.


Penny on the Coathanger

A penny is balanced on the hook of a coat hanger. The coat hanger is twirled around your finger and the penny doesn't fly off.


Balls on a Propeller

Balls sit in cups mounted on a swinging arm at .5m and 1.0 m. Calculate the period necessary to keep the ball in the outer cup and swing it around in time to a metronome.


Welch Centripetal Force

The angular velocity and mass needed to stretch a spring a certain distance are compared.


Variable Centripetal Force

A new design for the apparatus that allows any two of the three variables of mass, angular velocity, and distance to be kept constant.


Hand Rotator

Two 2kg spring balances are mounted on a rotator. Equal masses are attached to each and readings are taken at some rotational velocity.


Banked Track with Car

This model shows the forces involved when a vehicle transverses a steep embankment.


Banked Track w/ball

A steel ball rolled down an incline into a funnel reaches an equilibrium level where it revolves in a horizontal plane.


Rotating Plate

A turntable can be rotated at various angular frequencies. Objects can be placed at different radii. [A small platform (needs to be made) can be attached which will swing out to the correct slope for any angular velocity. A device for measuring force is also shown.]


Spinning Puzzle

Two balls in a box must be caught in end pockets simultaneously.


Rolling Chain

A flexible chain is spun on a motorized Disk. When pushed off the disk, it maintains it's rigidity as it rolls across the lecture bench. A block is put in its path to make it jump.

1D52. Deformation by Central Forces


Demonstration Name



Flattening Earth

Flexible hoops flatten when spun on a rotator.


Empty Jug by Swirling

A jug will empty faster when swirled. (an out-door Demo - too messy it a classroom)


Paraboloid of Liquid

A cylindrical container with some water is rotated at a constant speed.


Rotation Water Troughs

Two water containers are mounted on a rotating table. A rectangular container mounted radially shows half a parabola, and another formed in an arc of constant radius stays level.


Rotating Manometer

Tubing constructed in an "E" shape on its back is partly filled with water and rotated.


Project Mercury Parabola

Spin a dish of mercury and image a light bulb on the ceiling.


Balls in Water Centrifuge

Spin a semicircular glass tube filled with water containing 2 corks and aluminum balls.


Balls in Water Centrifuge

A long thin tube containing a brass ball, ping pong ball, and water is rotated.


Cork and Call Rotating in Water

One cork is tied to the bottom, one ball is tied to the top of two cylinders full of water at the ends of a rotating bar.


Rotating Corks in Water

Corks tied to the bottom of two jars full of water are first translated on a cart and then put on a pivot and rotated about the center.


Car Picture

A picture taken from inside a car of a candle, CO2 balloon, H2 balloon as the car is driven in uniform circular motion.


Mercury/Water Centrifuge

A spherical glass bowl is spun and mercury forms a equatorial band with water above and below.



A hand cranked test tube centrifuge.


Rotating Candle

Lighted candles in chimneys are rotated about the center of mass.


Paper Saw

A 6" paper disc placed on a dremmel tool cuts another sheet of paper. Typewriter paper will cut through other paper, Bristol board will cut through wood when spun at high speeds.


Rubber Wheel

A sponge rubber wheel with one spoke cut is rotated at high speed and viewed under stroboscopic light.


Rotating Rubber Wheel

A rubber wheel stretches to a larger radius when spun.

1D55. Centrifugal Escape


Demonstration Name



Broken Ring

A ball is rolled around the inside of a large open metal hoop. Students predict where the ball will go when it reaches the opening.


The Big Omega

A large wood circle with a gap is used with a boccie ball.


Cut the String

Using a homemade apparatus, a ball is put into a circular trajectory. A string connecting the ball to a rotating arm is quickly cut, and the ball flies off tangent to the original trajectory.


Grinding Wheel

Watch the path of sparks flying off a grinding wheel.


Spinning Disk with Water

Red drops fly off a spinning disc leaving traces tangent to the disc.


Block on a Rotating Table

An objects slides off a rotating turntable depending on the object's distance from the center of rotation or the rotational speed of the turntable.


Train Wrecks

Pictures of train wrecks at curves and some calculations.


Air Pump

Three mutually perpendicular discs are rotated about the intersection of two and air is drawn in the poles and expelled at the equator.

1D60. Projectile Motion


Demonstration Name



Throw Ball

Provide a large nerf ball, tennis ball, soft ball, or whatever ball is requested.


Ballistic Cart Launcher (CENCO)

The CENCO ballistic cart is equipped with a spring loaded vertical ball launcher. The ball is launched vertically into the air when a pin is pulled out by a string that is attached to a clamp on the table. The cart and ball move at constant velocity. The cart catches the ball some time later after the cart has gone underneath a bridge and the ball when over the bridge.


PASCO Ballistic Cart with Launcher

Cart moves on a track, inclined or level. It launches an ball upward.


Instructor on a Cart

Instructor sits on a rolling cart and throws a ball upward.


Ballistic Cart Goes Under a Bridge on an Incline

The same demo as 1D60.11 except the cart is moving on an incline.


Ballistic Cart on Incline

Some strobe pictures and drawings show the ball is always above the cart relative to the incline, but not always above the cart relative to the horizontal.


Drop & Shot

This older Welch Scientific apparatus is designed with a spring loaded device that simultaneously drops one steel ball while shooting another steel ball horizontally.


PASCO Monkey Hunter

This is the Pasco's version of "Shot the Target". A target (in this case a stuffed monkey) is released about 2 meters above the table top as soon as a projectile (a Ball) is fired. The ball then hits the target in midair as long as the system is properly alined.


Monkey Hunter on an Inclined Table

A simple and effective version using rolling balls on an inclined table.


Monkey Hunter (Monkey's Reference Frame)

Viewed from the free monkey frame, the projectile moves uniformly. Placing the hunter below the monkey can mislead students.


Projectile Range

Shoot a projectile out of the Pasco laucnher at 45 degrees then calculate the range for 30 or 60 degrees, and place the target accordingly.


Range of Gun

Use the tennis ball serving machine to find muzzle velocity, range, etc.


Parabolic Trajectory

Four launching ramps are mounted to a large magnetic surfaced coordinate system. Magnet based metal hoops can be repositioned easily so the ball passes through all the hoops. Looks very nice.


Parabolic Trajectory on Incline

A tennis ball covered with chalk dust is rolled across a tilted blackboard.


Air Table Parabolas

Pucks are projected across a tilted air table.


Parabolic Trajectory - Ski Jump

Apparatus for plotting parabolic trajectory by rolling balls down a ramp and launching them off a jump. There landing points can be plotted on carbon paper.


Parabolic Trajectory

A strobe picture is taken of the projectile motion of a golf ball. A method of analysis suited for a HS class is presented.


Adjustable Parabolic Form

Plumb bobs of lengths proportional to the square of their distance from the pivot point (1, 4, 9, 16, 25, 36, etc.) are hung from an arm with an adjustable angle. The bobs show the position of a projectile at equal time intervals which is launched from the pivot point with an initial angle equal to the angle of the main support arm.


Parabolic Trajectory - Water Stream

Apparatus Drawings Project No.33: The adjustable water nozzle has an arm extending in the direction of the nozzle with hanging arrows at intervals along the arm. Adjust the water pressure so the stream matches the arrow heads.


Water Trough Trajectory

Hook a nozzle to the house water through an additional regulator to reduce pressure fluctuations. Shoot at varying angles into a water trough.


Dropping The Bomb

A mechanism to drop a bomb in slow motion from a model airplane.



Juggling higher trajectories requires slower hand motion.